This invention relates to a method and apparatus for automatically doffing and donning take-up packages from a winder. The particular disclosure of this application is that of a textile winder which is used to wind yarn onto take-up packages suitable for further processing. However, the disclosure of this application can be utilized in other fields and for this reason relates broadly to strand processing.
At one time the textile winding process was a relatively simple one. Empty take-up packages were manually loaded onto each take-up station of a winder. The winder was manually activated to begin the winding process and when the take-up packages were full they were manually removed from the winder and empty take-up packages substituted in their place. However, the necessity of automating the winding process was recognized and, as with most other textile processes, the winding process was automated to the extent possible by providing means for automatically doffing and/or donning take-up packages in order to reduce the amount of labor necessary to operate the machines and decrease doffing time.
Therefore, what at one time was a relatively simple but labor-intensive manual procedure has become a relatively complicated automatic procedure. In the design of any automatic doffing and donning system, a number of design criteria should be considered and met in order to have a functionally sufficient system. First, the full take-up package must be moved relatively quickly and without damage to newly-wound yarn. The empty take-up package must be donned securely on each cycle. The cut yarn must be securely held while the doffing and donning process takes place and then securely attached to the empty take-up package before winding begins. While the yarn is being held care must be taken to make sure that the yarn does not come slack before it becomes attached to the new take-up package. Slack yarn can cause the yarn to break or pull loose from the take-up package when winding begins or snag on the chuck or other machine parts.
An automated doffing and donning system must also have a sensing mechanism which senses an improperly donned package or the absence of an empty supply package in the magazine. Such a system should also permit individual positions to be locked out of operation when less than a full machine is being operated.
It is most important to maintain positive control of the take-up package at all points during the doffing and donning process. As a practical matter, this means that the package should not be dropped by or rolled from the chuck into a conveyor or other discharge mechanism. Preferably, the full take-up package should be disengaged from the chuck directly onto the conveyor or other discharge means without intermediate handling of the package. This avoids needless complication in the mechanism.
In addition, the use of certain types of components in the doffing and donning mechanism should be minimized. Air cylinders, complicated electrical relays and the like require frequent and sensitive adjustment and are subject to sticking because of environmental contaminants. To the maximum extent possible cams, gears, and other mechanical or electro-mechanical devices should be relied upon because of their durability and ease of adjustment. In addition, the movement of the yoke between the winding, doffing and donning positions should be as simple as possible and should cover no more distance than is absolutely necessary. Reducing the distance between these various points in the winding mechanism reduces the possibility of tangles in the yarn and loss of control of the relatively heavy, full take-up package.
Prior art devices have attempted with varying degrees of success to meet the requirements of some of the abovestated criteria. Often, however, one or more of these problems have been solved only at the expense of creating other problems or, at the very least, increasing the mechanical complexity and hence, cost of the machine.